<s>
Differential	B-General_Concept
fault	I-General_Concept
analysis	I-General_Concept
(	O
DFA	O
)	O
is	O
a	O
type	O
of	O
active	O
side-channel	O
attack	O
in	O
the	O
field	O
of	O
cryptography	O
,	O
specifically	O
cryptanalysis	O
.	O
</s>
<s>
Taking	O
a	O
smartcard	O
containing	O
an	O
embedded	O
processor	O
as	O
an	O
example	O
,	O
some	O
unexpected	O
environmental	O
conditions	O
it	O
could	O
experience	O
include	O
being	O
subjected	O
to	O
high	O
temperature	O
,	O
receiving	O
unsupported	O
supply	O
voltage	O
or	O
current	O
,	O
being	O
excessively	O
overclocked	B-Application
,	O
experiencing	O
strong	O
electric	O
or	O
magnetic	O
fields	O
,	O
or	O
even	O
receiving	O
ionizing	O
radiation	O
to	O
influence	O
the	O
operation	O
of	O
the	O
processor	O
.	O
</s>
<s>
For	O
DES	B-Algorithm
and	O
Triple	B-Algorithm
DES	I-Algorithm
,	O
about	O
200	O
single-flipped	O
bits	O
are	O
necessary	O
to	O
obtain	O
a	O
secret	O
key	O
.	O
</s>
<s>
DFA	O
has	O
also	O
been	O
applied	O
successfully	O
to	O
the	O
AES	B-Algorithm
cipher	I-Algorithm
.	O
</s>
<s>
A	O
fault	O
injection	O
attack	O
involves	O
stressing	O
the	O
transistors	B-Application
responsible	O
for	O
encryption	O
tasks	O
to	O
generate	O
faults	O
that	O
will	O
then	O
be	O
used	O
as	O
input	O
for	O
analysis	O
.	O
</s>
